Ouch, I hope bub turns for your friend, posterior is SO PAINFUL. My DD was posterior and never turned..... so very painful! Although it was my first birth I have nothing else to compare it too but I just know it was so painful!! LOL (and no drugs!!)
Although it was only 9.5hrs.

My advice to your friend, get onto that spinning babies website (google it) and read about it and that lots of babies DO turn during labour into the correct position.

The best thing she can do is be as active as possible before and during the labour, standing up, swaying/rocking side to side, go with her body. I found it too painful to sit down and couldnt even sit to pee on the loo so I had no choice but to stand for the entire 9.5hrs of labour. But I think that helped me make it a shorter labour too!!!

GL to your friend